This application incorporates by reference Taiwanese application Serial No. 88210704, filed Jun. 29, 1999 and No. 88210705, filed Jun. 29, 1999.
1. Field of the Invention
The invention generally relates to a scanning apparatus using an indirect contact transmission in a scanning module, and more particularly to the techniques utilizing indirect contact arrangements to reduce vibration and thus improve the scanning image quality.
2. Description of the Related Art
Along with the development of new techniques and processes, the integration and the application of the multimedia has become a trend. The multimedia integrates various data types, such as text, image, and sound. To store or display data in the form of multimedia, many multimedia apparatuses have been developed. As for the image processing, a scanning apparatus such as a scanner is one of the apparatuses that users use to retrieve images.
FIG. 1 shows the sectional view of a conventional flatbed scanner. The scanner has a case 100. Above the case 100, there is a window glass 102 where the object to be scanned is placed. Inside the case 100, there is an image receiving apparatus 104. A lighting apparatus 106 is set up thereon. The flatbed scanner utilizes a dragging apparatus 108 to drive the image receiving apparatus 104. A connecting apparatus 110 is utilized to connect the image receiving apparatus 104 to the dragging apparatus 108. When the scanning process starts, the dragging apparatus 108 drives both the image receiving apparatus 104 and the lighting apparatus 106 via the connecting apparatus 110. The lighting apparatus 106 sends out light, which is reflected by the object placed on the window glass 102 afterward. The reflected light is received by the image receiving apparatus 104 and transformed to digital signals for later processing. In this way, the image of the scanned object is transformed to electrical signals and the image scanning process is completed. The technique mentioned above is for scanning opaque objects, such as document sheets. When scanning transparent objects, the scanning apparatus turns off the lighting apparatus 106 and turns on the lights (not shown in the drawing) mounted above the window glass 102. The other processes are similar to what mentioned above.
FIG. 2 is a perspective view of the transmission part of FIG. 1. In FIG. 2, the guiding shaft 112 is fixed inside the scanner. The image receiving apparatus 104 is set up and can slide along the guiding shaft 112. One side of the image receiving apparatus 104 is connected to the dragging apparatus 108, which drives the image receiving apparatus 104 to slide along the guiding shaft 112.
FIG. 3 is a perspective view of the transmission part in a scanning module of another conventional scanning apparatus. In FIG. 3, an image receiving apparatus 300 includes a photoelectric sensing component, e.g. a charge coupled device (CCD), a contact image sensor (CIS), or other sensing components that can transform a light signal into an electrical signal. Opposite to the image receiving apparatus 300, there is a securing apparatus 302 which can slide along a pair of guiding shafts 304A and 304B during the scanning process. Furthermore, a dragging component 306 is connected to the securing apparatus 302 by the connecting points 308. When scanning, the object to be scanned is placed on the securing apparatus 302 and the image receiving apparatus 300 is fixed. The dragging component 306 drives the securing apparatus 302 to move along the guiding shafts 304A, 304B via the connecting points 308. The image signals are received by the image receiving apparatus 300 for further processing. The above-mentioned dragging component 306 can be a steel rope, a belt, a gear train, a worm, or other components that can drive the securing apparatus 302.
Due to the fact that the dragging component 306 directly drives the securing apparatus 302, the vibrations generated by the dragging component 306 during the transmission process, such as the vibrations of the steel rope, the belt, the clutching of the gear train, the disequilibrium of the belt force, will be transmitted directly to the securing apparatus 302. These vibrations will cause many unnecessary relative movements between the fixed image receiving apparatus 300 and the moving securing apparatus 302. Thus, the quality of scanning is greatly affected. For a high-resolution scanning apparatus, such as a 2700 dpi (dot per inch) scanner, any unnecessary small vibrations can cause serious distortion of the image.
It is therefore an object of the invention to provide an indirect-contact component to reduce the vibrations and thus improve the quality of scanning. The indirect-contact component is added between the dragging component and either the securing apparatus or the image receiving apparatus. The indirect-contact component prevents the dragging component from being connecting directly to the securing apparatus or the image receiving apparatus. As a result, there will be fewer vibrations transmitted from the dragging component to the securing apparatus or the image receiving apparatus. Thus, the image quality can be effectively improved.
The invention achieves the above-identified object by providing an indirect-contact transmission arrangement for driving either a securing apparatus or an image receiving apparatus. The transmission arrangement includes a guiding shaft, a transmitting component, an indirect-contact component and a dragging component. The securing apparatus is used to place the scanning object, such as a document or a positive film. The image receiving apparatus is used to receive light signals reflected or transmitted from the scanned object. Then, the light signals are transformed to corresponding electrical signals for further processing. According to the invention, the dragging component connects and drives the transmitting component, which in turn drives either the securing apparatus or the image receiving apparatus. Here, the indirect-contact component can be an indirect-contact, gap-controllable component, a point-contact component or a low-rigidity, indirect-contact component. By this way, the vibrations generated by the dragging component during the transmission process will not transmitted directly to the securing apparatus or the image receiving apparatus. Therefore, relative vibrations between the scanning image and the image receiving apparatus can be greatly reduced during the scanning process and the image quality can be effectively improved.